To enhance the reliability of the simulation model of reference speed for metro train, an improved simulation model of reference speed is proposed by analyzing factors affecting train speed. The general simulation model of train reference speed usually takes the command acceleration of train as the response acceleration of train traction/braking system, while the improved simulation model takes into consideration the jerk limitation of metro train traction/braking system for the command acceleration and the dynamic process of response acceleration. The improved model was adopted to simulate the reference speed of Harbin Metro Line train, and the calculation results of the general model and the improved model were compared with the actual speed data. Results show that the reference speed data obtained by the improved model were more consistent with the actual speed data than those by the general model. Train reference speed is the basic parameter of speed tracking control of automatic train operation system. Its calculation accuracy can be improved by considering jerk limitation of command acceleration and the dynamic response process.